A major reason for the high cost of conventional test systems is the specialized nature of the tester architecture. Tester manufacturers typically employ a number of tester platforms that are not only incompatible across companies, but also incompatible across platforms. Because of these incompatibilities, each tester may require its own specialized hardware and software components that cannot be used on other testers.
Because of the dedicated nature of conventional tester architecture, all hardware and software must remain in a fixed configuration for a given tester. To test an IC, a dedicated test program is developed that uses some or all of the tester capabilities to define the test data, signals, waveforms, and current and voltage levels, as well as to collect the device under test (DUT) response and determine DUT pass/fail.
To increase flexibility and lower the cost of test systems, it would be desirable to connect and use pre-fabricated instrument cards from other systems and architectures within the test system, rather than design specialized hardware for the test system. For example, Peripheral Component Interconnect (PCI) eXtensions for Instrumentation (PXI) is the name of a system of electronic instruments comprised of a specified enclosure, a specified backplane and bus architecture, and plug-in cards that implement various types of instruments. PXI is a rugged personal computer (PC)-based platform for measurement and automation systems that combines PCI electrical-bus features with the rugged, modular, Eurocard mechanical-packaging of CompactPCI (cPCI), then adds specialized synchronization buses and key software features. FIG. 3 shows an example of a PXI card cage or enclosure 300, and FIG. 4 shows an example of a PXI card 400. Many companies produce a large variety of PXI instruments that perform specific functions, including programmable power supplies, arbitrary waveform generators (AWGs), digitizers (DGTs) and RF signal generators. PXI instruments are typically used as bench top test equipment, or as small functional test systems. However, they provide no means for system calibration and traceability other than self-calibration of individual PXI cards. Connections from the PXI card to an external device are generally through front panel cable connections, via BNC, SMA, SMB, or other connectors determined by the PXI card designer. PXI cards usually come with software drivers for Windows, LabView, etc. Compact PCI is similar to PXI, but with a slightly different form factor and bus structure.
Because there are many existing PXI and cPCI instrument cards, use of these instrument cards as part of a test system could drastically cut development time as compared to developing the same instrument from scratch for the test system. Also, when the expected production quantity of a given test system module is small, utilizing off-the-shelf instrument cards within the test module can be more economical than developing a new module.
However, because of the specialized and proprietary nature of the hardware and software in conventional test systems, heretofore it has been impossible to plug-in and use the instrument cards from other systems and architectures. ATE systems, for example, generally have a bus specification, board size, and environment that is different from PXI or cPCI. ATE systems generally provide for system calibration and traceability by taking measurements with a traceable instrument (such as a system digital voltmeter (DVM)) that is separate from the system module being calibrated, but is connected to the module by a bus provided by the ATE system. Connections from modules within the ATE system to the DUT are made through an interface that follows certain specifications for all modules and brings the signals from many modules to a loadboard or performance board that allows connection to the DUT. The interface is standardized for a given ATE system so that many types of performance boards for many types of DUTs can be connected to the ATE system. The ATE system has a particular software operating system that allows programming of all the modules in the system.
In addition to these electrical incompatibilities, physical incompatibilities have prevented instrument cards from other systems and architectures to be used in ATE systems. For example, ATE systems are typically designed to accommodate test system modules of a specified size (height, width, depth). These standard test system modules include a printed circuit board (PCB), and there is a size limitation on the components that can be mounted on top of the PCB without exceeding the specified depth (thickness) of the standard test system module. Instrument cards from other systems and architectures are generally too thick to be mounted on top of the PCB.
Because of the incompatibilities between the non-standard instrument cards (i.e. non-standard with respect to conventional ATE) and conventional test systems, previous uses of non-standard instrument cards have not been integrated into the test system and instead have been external to the test system and separately controlled.
Therefore there is a need to provide a carrier for adapting and integrating non-standard instrument cards from other systems and architectures into test systems such as ATE systems.